Apparatus for controlling breathing of oil-containing housings



" A. o. AUSTIN May 27,- 1930.

APPARATUS FOR CONTROLLING BREATHING OF OIL CONTAINING HOUSINGS Filed sept. 22, 1924 4 sheets-sheet' l IN VEN TOR @j A TTORNE YS May' 27, 1930 A. o. AUsTrN 1,759,971

APPARATUS FOR CONTROLLING BREATHING OF OIL CONTAINING HOUSINGS Filed Sept. 22, 1924 4 Sheets-Sheet 2 :wooo o o aoooo'o INVENTOR A TTORNE YS May 27, 1930. A, o. AUSTIN APPARATUS FOR coNTRoLLING BREATHING oF OIL Filed sept. 22, 1924 CONTAINING HOUS INGS sheets-sheet 5 GQGOOQOO -INVENTOR M44 Q BY 5l we ATTORNEYS` May 27, 1930. A. o. AUSTIN 1,759,971

APPARATUS FOR CONTROLLING BREATHING OF OIL CONTAININGHOUSINGS Filed Sept. 22, 1924 4 Sheets-Sheet 4 CDOOOOOOOOOOOOOOOOOO .il E 'L IN VEN TOR A TT ORNE YS Patented May 27, 1930 UNITED STAT-Es .PATENT OFFICE .ARTHUR O. AUSTIN, OF BABBERTON, OHIO, ASSIGNOB, BY HESNE ASSIGNIENTS, TO I THE OHIO BRASS COMPANY, OF MANSFIELD, OHIO', A. CORPORATION Ol'v NEW JERSEY APPARATUS FOR CONTROLLING BREATHING OF OILPCONTAINING HOUSINGS Application lcd ISeptember 22, 1924. Serial No. 739,008.

-f This invention relates to apparatus for use in connection with housings for transformers, condensers, oil circuit breakers, orother apparatus where the dielectric strength of 5 the oil is an important factor, and has for its object the provision of such apparatus which will control the'breathing of air by such housings and restrict or prevent the entrance of moisture thereto.

The invention is exemplied in the combination and arrangement of parts shown 1n the accompanying drawings and described in the following specification, and it is more articularly pointed out in the appended claims.

ln the drawings- Fig. 1 is t e vertical section of one form of trap and dehumidifier forming a portion of the present invention; K

Fig, E?, is an elevation of a transformer lcase Z@ having a pressure tank and trap connected therewith; Q

Fig. 3 shows the manner of applying theJ invention to a transformer housing havingV a conservator tank connected therewith;

Fig. l is an elevation showing the invention applied to a transformer tank having an air chamber in the top thereof.

ln electrical "apparatus containing oil, it is 30 of .the oil he maintained. This is exceedingly diiiicult where the oil is subjected to contact with air at normal atmospheric pressure. This is true even though a free circulation of air be prevented by a case which is nominally closed. Unless the case will withstand pressure and is tightly sealed, the expansion and contraction of the oil will cause a breathing action, drawing in fresh air when the oil contracts with the lowering tem' perature and discharging the air when the oil expands on a rising temperature.. This is particularly true when the oil is rather cool at all times, such as in oil circuit breakers and electrostatic condensers or transformers operating with a small load. This may readily happen in the case of water cooled transformers where the load is reduced on the transformer and the cooling water allowed to remain on. This may cause 59' a contraction in the oil with va consistent essential that the high insulating strengthV A14 to a receptacle 15 containing a dehumidi- .ted, the air will force up the`li uid in the restrictiona small enough compared with the,

drawing in ofA fresh air so that when theol becomes cooler thel air condensation readily takes place.

A small leak in transformers or other oil \containing cases which are otherwise lillv tightly sealed mayv cause trouble on a falling temperature due to condensation from the cooling of the incoming air. The expansion of the moist air coming in through the leak absorbs heat and tends to cause condensation.

It is the object of the present invention to eliminate these diiiiculties as far as possible.'- A large transformer case may draw in and discharge a considerable quantity of air, particularly`where the temperature and height of the oil changes. vlf the fresh air carry-v ing moisture comes in contact with the oil inthe transformer or in a conservator tank, the dielectric strength of the loil will be reduced in time. If the breathing actionA can1 be greatly'reduced or eliminated except at long intervals, the dielectric strength of the oil will tend to bel maintained.

One method of accomplishing this result is shownin F ig. 1 inv which 10 is an oil containing tank, housing electrical apparatus, the tank being connected througha ipe and valve 11 to one side of a trap 12.' 'llhe other side 13 of the trap is connected by a passage fying agent 16. The receptacle 15 is connected to the outside through an inverted .syphon or trap 1'? or by a breathing tube 18. When the oil in thevtank 10 expands, the air above the'e oil will be compressed and if the valve 11 is open, ressure willrbe exerted on the surface of t e trap fluid 19, which may be mercury or oil. This will cause the trap Huid to rise in the column 13 until air is forced through the opening or control valve at 20. The air will then rise in the column 13, pass over into the chamber 15 and esca .e th-rou h the breathing tube AY18. If this tu e is omittrap 17 and escape. It is possi le to prog5 vide a restricted opening at 2O or a baille as at 21 having several small openings so that air cannot go out in a rush, [displacing the trapping fluid entirely. By making these 10 cross-section of the .trap, the air will go out in small bubbles and the effective hei ht and pressure of the trap column will not lost.

If this is not done, the trap may have a tendency to blow. In order to prevent escape of the trapping fluid, either in handling or in operation, porous batlis 22 are used on each side of the trap. These baflles permit the passage of air, but may be'used to prevent ably backed up with a Wire screen or perforated metal' to provide mechanical strength.

Although the trap may prevent breathing rwith changes in temperature or pressure wit the case, it may not be advisable to prevent puassage of air under extreme conditions. T 'sanay be regulated by the height of the vertical columns composing the trap and by the weight of the fluid in the trap. As shown in Fig. 1, the trap is designed to relieve the difference in pressure when the pressure .inside of the tank or case becomes sli htly below atmospheric pressure.

f the arms of the trap in some instances are found to be too long as in the case where a light fluid, such as oil, is used, several traps may be used in 'series to obtain the desired pressure. To obtain dry air at all times, it

' 1s advisable fto take the incoming air througha chamber which will take out the water. One method is4 to fill a chamber 15 with calcium chloride 16. If the breathing tube 18 is closed by a valve 18 or is omitted entirely,

the trap 17 prevent a breathing of the chamber for relatively small -fluctuations of pressure. A slight breathing, even though air does not pass the main trap, would tend to use up the store of calcium chloride, lime,

or other dehumidifying agent. prevented to a considerable extent by Y 23 and overflow from the end of the trap 17 Where the walls of the chamber 15 are made of glass, the condition of this chamber can be readily determined at all times. It is evident that the dehumidifying chamber may be placed between the main pre'ure regulating trap and the case. This has the advantage in l that minor fluctuations in-.the' columns of the trap and inthe expansion of the`air in the' dehumidifier will not tend to use up the dehumidifying agent. Any breathing of the Aair between 'the case and the dehumidifier Willl be an advantage as it will tend to take water out of this air. In this ,case it is usually necessary to eliminate the trap for the dey humidifier 'or provide a seriestrap, compsed of a number of U-tubes in series, inorde'r to prevent the drawing in lor discharge of air:

through this trap. The valve 11 may. be used to shut o' the air supply or prevent flow while the apparatus is being charged or regulated. It is evident that the amount of fluid in the trap can be changed to regulate the pressure.

Fig. 2 shows one application to a transformer tank. In this case the trap is connected to an auxiliary breather tank 30. This tank has a pipe 3l which extends nearly to the.

bottom and which is connected to the top of the transformer 'case through the valve 32.

T he bottom of the tank 30 is connected to the transformer case by the valve 33. Under operating conditions, the transformer case should be full of oil and the tank 30 partially full of oil. Under falling temperature and a contraction of the oil there will be a tendency for a vacuum to form in the top of the transformer case 36 and the air in the upper portion of the tank will expand due to the decrease in pressure in the case 36 and force the oil up through the pipe and valve 31 and 32 into the transformer case to equalize the pressure. If the pressure is reduced below the setting of the trap, air will be drawn in through the dehumidifier 35 up through trap 34. This air will enter the up r part of the tank 30. If the tank 30 has s cient volume, no air will pass over into the transformer case through the pipe and valve 31 and 32. It is understood that the valve 33 isclosed at all f times, except in the case of making repairs to the transformer and regulating the height of the oil in tank'30, which will be explained later. If there is any air in the transformer case during a rising temperature this air will be dispensed through the valve 32 and pipe 31V into the tank 30. By placing the entering Ipoint high on the transformer case, it willbe seen that any air in the transformer case will be discharged up to this point and replaced on the falling temperature by .dill which willbe forced up through the pipe 31. This method then may be. used tokeep the main transformer case filled with oil although -ios the oil in the breather tank 30 may be at a lower level. The breather tank may be large so that the fluctuation in pressure can be controlled within fairly narrow Ordinarily the valve 33 is closed as this will tend to discharge any air in the top of the transformer case in line with the valve 32. If the transformer or oil containing case has no leaks, the valve 33 may be opened after the .air is pumped out in which case the tank 30 will permit circulation of the oil. Where the transformer tank is full of oil,` it is frequently necessary to provide storage for oil before Y opening up the ltransformer case. Where the tank 30 is empty or only partially iilled, the

valve 33 may be. opened and asV soon as the airis admitted to the transformer case, the

oil will rise in the breather tank 30 and drop in the mainA transformer tank 36.

Fig. y3 shows the adaptation of a trap. system 75 in series with a dehumidifying chamber 76 connectedto the air space 77 of a conservator tank 78 through a pipe 79.

The conservator tank being above the height of the transformer or oil containing tank 80 will keep the transformer tank full at all times. The trap system and dehumidiying chamber 76 may be used to prevent excessive breathing in conservator tank 78 so that the high insulation of the oil may be maintained.

Fig. 4 shows the adaptation of a trap system 81 in series4 with a dehumidifying chamber 82 connected to the air space 83 to an oil tank of a' condenser 84, connection being made through the valve and connecting pipe 85. It is evident that as the princi al object is to dry and control the nature o the incoming gas or air, that a discharge trap without the dehumidiying chamber` may be used for the relief of pressure above that of the atmosphere, permitting same to discharge directly into the air. This t of z5 trap was shown in former application erial No. 722,204, filed June 25, 1924.

I claim 1. The combination with a casing for electrical apparatus having expansible liquid y therein, of a trap connected with said casing,

a receptacle having a moisture absorbing material therein, said receptacle being arranged in series with said casin and trap, and

rous bales for preventing the escapey of, as 'quid from said trap.

2. The combination with a casin for electricall apparatus having expansib e liquid therein, of an expansion chamber connected with said casing for maintaining the liquid level in said casing when the liquid therein expands and contracts, a trap connected with said expansion chamber to prevent passage tra and areceptacle having moidzure ab- ,sor ing material therein arranged in series with said trap and expansion chamber to absorb moisture from air passing through said trap to said ex ansion chamber.

5. The combination with a tank for containing liquid under pressure, of a conduit connected with the upper part of said tank and having a trap therein, a chamber having a partition therein providing two compartments communicating at the bottom of said partition, means for connecting the upper part of one of said compartments with said trap,\and means for connecting the upper partof the other of said compartments with said tank. t

In testimony whereof I have signed my name to this, specification on this 18th day of Sept. A./D. 1924.

' ARTHUR O. AUSTIN.

'of air between said chamber and atmosphere for relatively small variations in pressure in said chamber but permitting passage of air for greater variations in pressure, and means for dehumidifying the air which p i through said trap.

trical apparatus having anexpans le liquid therein, of an expansion chamber 'having a gas therein for maintaining the liquid level in said casing, atrap having one leg thereof connected with said expansion chamber, and a receptacle having moisture absorbing material therein for removing moisture from air which enters said expansion chamber through said trap.

` 4. The combination with a sealed casing having an expansible liquid therein, of an expansion chamber connected with said casing having gas under pressure for maintaining the liquid level in said 388mg trap connected with said expansion chamber, bafefles for preventing escape of liquid from said 3. The combination with a casingbfor elec- 

